1. Field of the Invention
The present invention relates to jigs for use in the manufacture of a joined structure of a perforated ceramic plate and a ceramic tube, and a method for manufacturing a joined ceramic structure by the use of the above-mentioned jigs.
2. Description of the Related Art
Ceramics have high heat resistance and heat-insulating properties, electrical and electronic characteristics such as insulation, conductivity, magnetic and dielectric properties, and excellent mechanical properties such as wear resistance, whether the constitutional composition of the ceramics is an oxide or a monoxide. These ceramics have already been used as materials for various structures, and the research and development of the ceramics have also been advanced.
In the case that the ceramics are used as materials for mechanical parts and structural members, these mechanical parts and structural members are required to have various shapes, and combinations of the respective parts and members are also demanded. Therefore, it is often required to join and fix the ceramic parts and elements to each other at various portions except the integrally molded ceramic structures.
Among various kinds of parts and members, joined structures each comprising a combination of a plate-like member and another member having a different shape have often been used as the mechanical parts and the structural members, and structures formed by inserting tubes into a plurality of holes perforated through the plates have also often been used. For example, in a shell-and-tube type heat exchanger or the like, a member is used which can be formed by joining and fixing perforated plates having a plurality of holes to both the end portions of a plurality of ceramic tubes.
As a method for preparing a joined ceramic structure in which the perforated plates are joined to both the end portions of each of the plurality of ceramic tubes, there is known a method which comprises inserting the end portions of the tubes of sintered ceramics into through-holes 3 of such perforated plates 1 of unsintered ceramics having the plurality of through-holes 3 as shown in FIG. 7, and then heating these members to fire them, thereby integrally joining both the members to each other by the utilization of a difference between firing shrinkage ratios of both the members (this joining technique utilizing the difference between the firing shrinkage ratios will be hereinafter referred to as "firing join"). In this method, the tubes of the sintered ceramics having the small firing shrinkage which scarcely shrink are held by the perforated plates of the unsintered ceramics having the large firing shrinkage owing to the shrinkage of the through-holes by the firing, whereby both the members can be integrally joined.
In this case, the firing can usually be carried out in such a condition as shown in FIG. 8 where in a sagger having a sealed structure for the purposes of preventing contamination with carbon and the like from furnace materials and of regulating an atmosphere, a setter 4 is placed, tubes 2 are stood on this setter 4 so as to be vertical to a floor surface, and perforated plates 1 are positioned at both the upper and lower end portions of the tubes 2 by the use of jigs 5.
In this connection, the jigs which can be used in the manufacture of the aforesaid joined ceramic structure are merely inserted between the upper and lower perforated plates, and they do not have a structure which can be fixed by the perforated plates. Therefore, during the firing step, a position deviation easily occurs, the perforated plates might be broken, and the shape accuracy and airtightness of the joined structure tend to deteriorate, owing to the shrinkage of the perforated plates by the firing.